Reconstituted tobacco

ABSTRACT

A process for manufacturing a reconstituted tobacco composition wherein a foamed slurry is created from tobacco, a foaming agent or adhesive and ethylhydroxyethyl cellulose having an ethoxyl D.S. of 1.2 to 1.6 and a hydroxyethyl M.S. of 0.5 to 1.2. The foamed slurry is shaped while maintaining the temperature thereof below the gelatin temperature of the ethylhydroxyethyl cellulose and dried to form a shaped sheet or rod of predetermined moisture content. The foaming agent employed may be a synthetic or natural gum or water dispersible protein.

United States Patent [72] Inventor [54] RECONSTITUTED TOBACCO 2 Claims,No Drawings [50] Field of Search 131/17, 140-144 [56] References CitedUNITED STATES PATENTS 3,528,434 9/1970 Halter et al. 131/140 C OTHERREFERENCES Encyclopedia of Polymer Science and Technology: Vol. 3, pub.by lnterscience Publisher s, 1965, NYC, p. 491 cited.

Primary Examiner-Melvin D. Rein Attorneys-George W. Price and MurraySchaffer ABSTRACT: A process for manufacturing a reconstituted tobaccocomposition wherein a foamed slurry is created from tobacco, a foamingagent or adhesive and ethylhydroxyethyl cellulose having an ethoxyl D8.of 1.2 to 1.6 and a hydroxyethyl MS. of 0.5 to 1.2. The foamed slurry isshaped while maintaining the temperature thereof below the gelatintemperature of the ethylhydroxyethyl cellulose and dried to form ashaped sheet or rod of predetermined moisture content. The foaming agentemployed may be a synthetic or natural gum or water dispersible protein.a

RECONSTITUTED ronxcco This invention relates to improved smokingproducts made from foamed tobacco slurries. More particularly thisinvention relates to the use of a particular grade of ethylhydroxyethylcellulose as a foam-stabilizing agent in foamed reconstituted tobaccocompositions and to the novel and beneficial properties that resulttherefrom.

1n U.S. .Pat. No: 3,364,935, U.S. Pat. No. 3,404,690, U.S. Pat. No.3,404,691 and U.S. Pat. No. 3,410,279, Moshy and Germino describedinventions to produce a foamed tobacco slurry which, when cast orotherwise formed into a desired shape and suitably treated will provideasmoking article with an open cellular structure. The Moshy and Germinoinventions involve processes for combining a foaming agent, afoam-stabilizng agent and tobacco, at least one element of said mixturebeing adhesive, creating a tobacco foam slurry from said mixture,forming said slurry into a predetermined-shape and drying said shapedslurry to a preselected moisture content to produce a stable foamedproduct in which tobacco particles are spaced from each other byagaseous media. During the process of pumping and shaping the foamedtobacco slurry, the work done on this slurry can cause some degree offoam breaking and collapse. Furthermore, during the process of dryingthe shaped foamed tobacco slurry, further foam disruption and collapsecan occur. Although the practice of the Moshy and Germino patents doesresult in foamed tobacco products, the lack of optimum foamstabilization characteristics using the foam-stabilizing ingredientsspecified makes the production of foamed tobacco products with exact.density characteristics difficult to obtain and control. Since theuniformity of weight, firmness and draw of smoking articles produced bythis process depends on control of the ultimate foam densitycharacteristics, it is apparent to those involved in research in thisarea that a significantly more stable foamed tobacco slurry is requiredto provide the degree of foam density control during transfer, shapingand drying which is necessary for a commercially acceptable process andproduct.

Accordingly, it is an object of this invention to provide an improvedfoamed reconstituted tobacco product'and an improved process for makingsame.

It is a further object of this invention to provide foamed reconstitutedtobacco products which can be made to exacting density specifications,and a process for accomplishing same.

It is still a further object of this invention to provide reconstitutedtobacco products which, because they are made by a process which resultsin reproducibility of product density, will exhibit commerciallyacceptable reproducibility of product weight, compressibility andpressure drop (draw) as well.

It is another objective of this invention to provide foamed tobaccoproducts with readily controllable product densities which are achievedthrough the usage of a small percentage of a particular grade of aparticular water-soluble cellulosic derivative as the foam stabilizingagent.

Additional objectives will become apparent from the description of theinvention which follows:

It should be understood throughout the discussion that this inventioncontemplates manufacture of foamed reconstituted tobacco compositions inthe shape of sheet, rods, cylinders, plugs, shreds and the range offorms associated with the production of hundreds of different shapes ofcigars. 1n the case of foamed reconstituted tobacco sheet, this sheetmay be made at the thickness of the ultimate smoking article, and theagent in a reconstituted tobacco slurry of the type described by Moshyand Germino at a level of at least 0.3 percent, the superior stabilityof the foamed tobacco slurry during the manufacturing operationsresults, as described above.

The purpose of the following three paragraphs is to explain the useherein and in the prior art of the tenns degree of subsmoking articlemay be cut from such sheet. As an alternative,

stitution (D.S.) and molar substitution" (M.S.).

There are three hydroxyl groups in each anhydroglucose unit in thecellulose molecule. D.S. is the average number of hydroxyl groupssubstituted in the cellulose per anhydroglucose unit. M.S. is theaverage number of moles of reactant combined with the cellulose peranhydroglucose unit. For the alkyl, carboxyalkyl, or acyl derivatives ofcellulose, the D.S. and M.S. are the same. For the hydroxyalkylderivatives of cellulose, the M.S. is generally greater than the D.S.The reason for this is that each time a hydroxyalkyl group is introducedinto the cellulose molecule, an additional hydroxyl group is formed withitself is capable of hydroxyalklation. As a result of this, side chainsof considerable length may form on the cellulose molecule. The M.S./D.S.ratio represents the average length of these side chains. Thus, from theforegoing, it will be seen that the total D.S. of a cellulose derivativecan be no higher than 3, whereas the M.S. may be considerably higherthan 3, depending on the extent to which side chains are formed.

With a mixed ether such as ethylhydroxyethyl cellulose, the ethoxylcontent is reported as D.S. since, as noted above, the D.S. and M.S.must be the same for this constituent. The hydroxyethyl substituent, onthe other hand, is reported as M.S. since addition to side chains ispossible in this case.

The two most widely used methods for determining M.S. are theZeisel-Morgan method and the terminal methyl method. The Zeisel-Morganmethod is reported beginning at page 500, vol. 18, 1946, of Industrialand Engineering Chemistry, Analytical Edition. The terminal methylmethod is reported by Lemieux and Purves beginning at page 485, vol.258, 1947, of Canadian Journal of Research". Some are of the opinionthat perhaps the latter method is more accurate. However, all thoseskilled in the art realize that it is quite difficult to obtain a highdegree of accuracy in determining M.S. at high M.S. levels, and that theaccuracy of neither of these methods is as high as desired. However, theD.S. and M.S. values specified herein were determined by the mostaccurate methods known and, at the substitution levels of theethylhydroxyethyl cellulose of choice, are quite satisfactory. Theethoxyl D.S. was determined by the terminal methyl method and thehydroxyethyl M.S. was determined by the Ziesel-Morgan method.

Other grades of ethylhydroxyethyl cellulose are referred to in the priorart. The use of the normal commercial grade of ethylhydroxyethylcellulose as the adhesive in reconstituted tobacco compositions isreported by Rosenberg and Schmidt in U.S. Pat. No. 3,042,552 (July 3,1962 The ethoxyl content of this material is listed by Rosenberg andSchmidt as l7 -l8 percent (D.S. =0.8 and the hydroxyethyl content atabout 17.3 percent (M.S. =0.9 The ethylhydroxyethyl cellulose used byRosenberg and Schmidt is different in composition than that of thepresent invention, which involves an ethoxyl degree of substitution of1.2 to 1.6 and a hydroxyethyl molar substitution of 0.5 to 1.2 Thedifferences are even greater than one might anticipate from thesubstitution differentials, and are in fact differences in kind, notjust in degree. The normal ethylhydroxyethyl cellulose (EHEC) used byRosenberg and Schmidt will dissolve in water at temperatures up to about60 C. The EHEC of this invention will not dissolve in water if thetemperature is over 25 C. and, for complete solubilization, thetemperature should be below 15 C. The Rosenberg and Schmidt EHEC willgel or precipitate from aqueous solution when the temperature is raisedto 55 70 0, depending on the exact substitution; the EHEC of the presentinvention will gel or precipitate from aqueous solution when thetemperature is raised to about 3238 C. The Rosenberg and Schmidt EHEC isinsoluble in methanol or ethanol or percent isopropanol; the EHEC of thepresent invention is completely soluble in these solvents. in spite ofthe fact that both materials are ethylhydroxyethyl celluloses, thedifference in substitution between the two grades have resulted inphysical and chemical properties for the two grades of gum that are asdifferent from each other as one would expect from adhesives of entirelydifferent classes.

The properties contributed to foam stabilization by the incorporation ofthe EHEC of the present invention are also radically different fromthose which are obtained using other carbohydrate, protein or syntheticgums at similar levels in the formulation, or even at substantiallyhigher levels. Furthermore, the foam stabilization properties areradially different from those which are obtained with any othercellulose ether and even from other grades of ethylhydroxyethylcellulose with different levels of substitution.

It should be noted that Moshy and Germino employed, as foaming agents,adhesives such a animal gums, such as glycogen, plant gums andderivatives, such as cellulose ethers, cellulose esters, startches,starch ethers, starch esters, amylose, amylopectin and their ester andether derivatives, locust bean gum, guar gum, gum arabic and relatedseed gums and plant exudate gums, marine plant gums, such as algins,carrageenans, laminarins and agar, and microbial gums such as thedextrans, phosphomannans such as USDA B-1459 and 8-1428, and thegluconic acid microbial-containing gums such as the USDA Y-1409 gums,and water-dispersible protein classes such as animal proteins such ashydrolyzed keratins, egg albumin, and vegetable proteins such as glutenand synthetic gums such as polyvinyl alcohol, polyoxyethylene andpolyacrylamide.

These materials, although foamable with Moshy and Germino compositions,were quite unstable and required the addition of a foam-stabilizingagent initially or after foaming, or the use of a blowing agent, inorder to provide any measure of foam stability. The foam-stabilizngagents of the Moshy patents were ionic and nonionic surfactantsconsisting of the salts of the sulfate esters of thealkylphenoxypolyoxyethylene ethanol, the salts of sulfate compounds ofthe type N-methyl- N-oleoyl taurine, sorbitan esters such a sorbitanmonostearate (Span 60 or the monooleate (Span 80 ethylene oxide-sorbitolcondensation products, and lecithin and lecithin derivitives. Suchmaterials in addition to that fact that they do not provide the desireddegree of foam stability for optimum process control, also contributeoff-aromas on combustion, even when used at low levels.

Based on the Moshy and Germino disclosures of the foam instability whenany one of their many foaming agent-adhesives are incorporated intobacco slurries at generally high levels to provide the proper adhesivequalities, it was quite unexpected and novel to find that the EHEC ofthis invention, a cellulose ether, should function as an exceptionalfoam-stabilizing agent when used at low concentrations in the product ofonly 0.3 to 2.5 percent. It is also interesting to note that the closestmaterial to the EHEC of this invention, the EHEC of the Rosenberg andSchmidt patent, does not provide such foam stability when employed inotherwise identical formulations. The uniqueness of the EHEC of thisinvention indicates that the problem of tobacco foam stabilization toboth mechanical work and heat energy is most complex and, as yet,without theoretical prediction or explanation.

It should be noted that the foam stabilization characteristic associatedwith the use of the particular EHEC of this invention is due to thedegree of substitution of the ethoxyl and hydroxyethyl substituents,with no significant effect of the viscoity of the gum on this property.Differences in product strength are also not obtained when differentmolecular weights or viscosities of this EHEC are employed, since at thelow usage concentrations involved in tobacco foam stabilization, theEHEC does not function as an adhesive to any measurable extent.

In the practice of this invention, any of the processing modificationsemployed in the four Moshy and Germino patents may be employed, withethylhydroxyethyl cellulose with an ethoxyl D5. of 1.2 to 1.6 and ahydroxyethyl molar substitution of 0.5 to 1.2 being used at aconcentration of 0.3 to 2.5 percent of the composition (Dry basis) inplace of the foam stabilizing agents employed by Moshy and Germino.Accordingly, the stabilized tobacco foam may be prepared by: (a) foamingthe foaming agent, then adding tobacco and the foam-stabilizing agent(the EHEC of this invention); (b) foaming the foam stabilizing agent(the EHEC of this invention), then adding tobacco and the foaming agent;(c) foaming a foaming agent, foam stabilizing agent (the EHEC of thisinvention) mixture, then adding tobacco; (d) foaming a mixture offoaming agent, foam-stabilizing agent (the EHEC of this invention) andtobacco; (e) foaming a mixture of foaming agent and tobacco, then addingfoam-stabilizing'agent (the EHEC of this invention); (f) foaming amixture of foam-stabilizing agent (the EHEC of this invention) andtobacco, then adding foaming agent.

It should be noted that if tobacco is treated in a manner such that itsadhesive properties are fully developed, such as in Light and OsborneUS. Pat. No. 661,762, then addition of one of the adhesive foaming agenttypes referred to by Moshy and Germino is not necessary. Accordingly,(f) above, for example, would involve only foaming a mixture offoam-stabiling agent (the EHEC of this invention) and tobacco, shapingand drying to a preselected moisture content.

Optional additives in the formulations of this invention includehumectants or plasticizers, ash whiteners, fungicides, fibers forreinforcement and cross-linking or insolubilizing agents for resistanceto water. Use of such additives, of course, depends on the particularproperties required in the final smoking article.

In working with the dispersions and foamed dispersions containing theEHEC of this invention as the foam-stabilizing agent, it must beremembered that this material has a low thermal gelation temperature.Care must be taken at each step of the tobacco slurry preparation,foaming, transfer and shaping, to insure that the thermal gelationtemperature is not approached, other gelatin or precipitation will occurand the foam stabilization property will be lost.

The following examples are provided as further illustrations of theinventive concept, and should not be construed as limitations on theinvention.

EXAMPLE 1 A tobacco slurry is prepared by adding, with mild agitation,0.2 parts (dry basis) of a 3.0 percent dispersion of refined sulfitepulp to one part (dry basis) of a 2 percent aqueous dispersion ofmethylcellulose with a viscosity of 15,000 c.p.s. The pulp dispersionand the methylcellulose dispersion are each at about 5 C. before mixing,and 10 C. or less after the mild agitation. To this mixture is added,with mild agitation, 0.03 parts (dry basis) of a 2 percent solution ofethylhydroxyethyl cellulose with an ethoxyl D.S. of 1.2 a hydroxyethylM.S. of 0.5, a viscosity of 15,000 c.p.s. and at a temperature of 5 C.Also, a 20 percent aqueous dispersion of minus mesh Bright tobacco leafis added, and the completed slurry is mixed for 15 minutes, to produce auniform dispersion at a temperature of 16 C. The tobacco slurry isfoamed to a density of 0.55 grams/co, using Hobart mixer with a wirewhip, and

the resultant foamed slurry is cast on a moving stainless steel belt ata thickness such that the tobacco slurry film after drying, will weigh 6grams per square foot. The foamed tobacco sheet product is 24 milsthick, as compared to a conventional nonfoamed product of the sameformulation which would be only 6 -7 mils thick at 6 grams per squarefoot It may be shredded and used as a cigarette filler.

EXAMPLE 2 A 6 percent solids dispersion of refined burley stem pulp isprepared to a Schopper-Riegler freeness of minus 300 cc. using the stempulp preparative procedure described by Light and Osborne in US. Pat.Ser. No. 661,762. To 6 parts (dry basis) of this tobacco stem pulp isadded, with agitation, 4 parts (dry basis) of a percent dispersion ofminus 120 mesh Wisconsin leaf dust and 0.25 parts of a 2 percent aqueousdispersion of ethylhydroxyethyl cellulose with an ethoxyl D8. of 1.6, ahydroxyethyl MS. of 1.2 and a viscosity of 300 c.p.s. Mild agitation iscontinued until a uniform dispersion is obtained, with care being takento prevent the slurry temperature from rising above 20 C. The resultanttobacco slurry is foamed to a density of 0.60 grams per cc. and may becast and dried in sheet form as in Example 1, or extruded or molded toproduct, after drying, a porous self-supporting rod or other core shapessuitable for wrapping as a cigar.

What is claimed is:

l. The process of manufacturing a smokable product comprising creating afoamed slurry from a foaming agent or adhesive, tobacco particles, waterand 0.3 percent to 2.5 percent, by weight of the nonsolvent ingredients,of ethylhydroxyethyl cellulose with an ethoxyl D8. of 1.2 to 1.6 and ahydroxyethyl M .S. of 0.5 to 1.2, shaping said foamed slurry whilemaintaining the temperature thereof below the gelation temperature of 20of ethylhydroxyethyl cellulose with an ethoxyl D8. of 1.2 to 1.6 and ahydroxyethyl M.S. of 0.5 to 1.2 and a foaming agent in amounts between 3percent and 15 percent by weight of the nonsolvent ingredients andselected from natural or synthetic hydrophylic gums in which the naturalgums are selected from carbohydrate classes including the animal gumssuch as glycogen, plant gums and their derivatives, such as celluloseethers, cellulose esters, starches, starch ethers, starch esters,amylose, arnylopectin and their ester and ether derivatives, locust beangum, guar gum, gum arabic and related seed gums and plant exudate gums,marine plant gums, such as algins, carrageenans laminarins and agar, andmicrobial gums such as the dextrans, phosphomannans such as the USDA8-1459 and 13-1428, and the gluconic acid microbial containing gums suchas the USDA Y-l409 gums, and protein classes including water dispersibleproteins such as animal proteins such as hydrolyzed keratins, eggalbumin, and vegetable proteins such as gluten, and the synthetic gurnsare selected from the group consisting of polyvinyl alcohol,polyoxyethylene and polyacrylamide shaping said foamed slurry whilemaintaining the temperature thereof below the gelation temperature ofsaid ethylhydroxyethyl cellulose and subsequently drying said slurry toa shaped sheet or rod form of a predetermined moisture content.

2. The process of manufacturinG a smokable product comprising creating afoamed slurry from tobacco particles, water, 0.3 percent to 2.5 percentby weight of nonsolvent ingredients of ethylhydroxyethyl cellulose withan ethoxyl D.S. of 1.2 to 1.6 and a hydroxyethyl M.S. of 0.5 to 1.2 anda foaming agent in amounts between 3 percent and 15 percent by weight ofthe nonsolvent ingredients and selected from natural or synthetichydrophylic gums in which the natural gums are selected fromcarbohydrate classes including the animal gums such as glycogen, plantgums and their derivatives, such as cellulose ethers, cellulose esters,starches, starch ethers, starch esters, amylose, amylopectin and theirester and ether derivatives, locust bean gum, guar gum, gum arabic andrelated seed gums and plant exudate gums, marine plant gums, such asalgins, carrageenans laminarins and agar, and microbial gums such as thedextrans, phosphomannans such as the USDA B-1459 and B-1428, and thegluconic acid microbial containing gums such as the USDA Y-1409 gums,and protein classes including water dispersible proteins such as animalproteins such as hydrolyzed keratins, egg albumin, and vegetableproteins such as gluten, and the synthetic gums are selected from thegroup consisting of polyvinyl alcohol, polyoxyethylene andpolyacrylamide shaping said foamed slurry while maintaining thetemperature thereof below the gelation temperature of saidethylhydroxyethyl cellulose and subsequently drying said slurry to ashaped sheet or rod form of a predetermined moisture content.